[Amps] Need Smarter Than I Am Help.

[Joe]

Thanks for the lead!

Now can anyone scan those page(s) and e mail them to me?

I do not have access to any of the Handbooks.  I had the CD version, but 
can not seem to find it.

Joe WB9SBD

On 10/11/2021 10:26 AM, gudguyham wrote:
> As far as Q, most ARRL handbooks have charts based on plate impedance 
> and show C1 L C2 values for a Q of around 10-12.  Look at the chart 
> that fits your plate impedance.  Set C1 and C2 to the values on the 
> bands and adjust L for maximum output or a peak in output at those 
> settings.  When you find the peak for L that is where you want L to 
> be.  Then tweak C1 and C2 for maximum output, they should only need a 
> small tweak.  Note the L setting.  Your Q will be very close to 10-12 
> that way. Q is not overly important unless it’s totally out of the 
> realm of reality.  Too many stress out about this.  Most amps believe 
> it or not take whatever Q they can get on the lowest and highest band 
> and leave it at that.  Some amps suck big time on the high and low 
> ends.  The best 3-500 amp I’ve seen with very good low and high band 
> operation is the Kenwood 922.  Worst I’ve seen is Ten Tec Centurian.  
> The 922 is miles ahead of anything in its class.
>
>
> Sent from the all new AOL app for iOS 
> <https://apps.apple.com/us/app/aol-news-email-weather-video/id646100661>
>
> On Monday, October 11, 2021, 10:34 AM, Joe <nss at mwt.net> wrote:
>
>     This IS a valid question.
>
>     I am not sure about others, In my case it was 90% Cost. With side
>     effect
>     benefits.
>
>     I knew that for high duty cycle modes you should run this amp at
>     reduced
>     power.
>
>     I was using the SB-220 at 500 watts output in a RTTY contest. But I
>     guess even that low was not low enough for about 4 hours into the
>     contest the magic smoke that makes this stuff work escaped from
>     the HV
>     transformer.
>
>     Shopping around for a replacement transformer gave me a major case of
>     sticker shock. I bet the cost of all the replacements I was
>     finding was
>     close to the cost of the AMP when it was bought new! I was ready to
>     either shelf the amp or sell it.
>
>     Then thought, well voltage is voltage, is there anything else out
>     there
>     that can make the same or similar voltages and would work.
>
>     And there is, Yes it is considerably larger than the original
>     transformer, so it required some modifications of the chassis of
>     the amp
>     to allow it to fit. But it does fit. Barely!
>
>     And it cost 25% of what all the replacement transformers were wanting.
>
>     And yes with the raised voltage and the cost savings I decided to
>     make
>     changes to the whole HV section too. Changed to safely handle the new
>     parameters. Whole new caps and resistors, New Harbach HV board
>     etc. I do
>     not know if it is the new cap bank, or the transformer itself, but
>     it is
>     incredibly stiff compared to the stock one that was in there. The HV
>     voltage drop from no load to max out is not even 100 volts! like
>     3700 no
>     load to 3600 at 2Kw.
>
>     The AMP runs stone cold, it is HARD I mean HARD to get the plates to
>     even turn red, never mind the orange that people say it should
>     often do
>     to "Getter". At 1500 Watts OUT, Even with it transmitting a dead
>     carrier, after minutes of making RF, the plates were still gray.
>     At 2Kw+
>     out, during a normal like Sweepstakes exchange of length, you may get
>     some Red plates. Orange needs the same 2Kw AT A SOLID CARRIER for
>     about
>     a solid minute to get to the orange state.
>
>     Yes the output network needs work. Unless I run 1400+ watts all the
>     time. Then the network runs fine!
>     I have learned that I need more "L"
>     But that is a work in progress.
>     Trying to find good new taps was a pain. So in the amp now is a 18uH
>     roller inductor.
>     So now the only thing the output bandswitch is now doing is add
>     that cap
>     when on 80 meters.
>
>     Now I am still lost when it comes to this "Q" thing.
>
>     And what are the optimal settings for this network. That roller
>     changes
>     everything.
>
>     I can get a perfect 1 to 1 match, with the Plate cap at absolute
>     minimum
>     meshed state, and I also can get a perfect match, with the cap
>     like 50%
>     meshed, like where it would be normally on 40 meters, but still on
>     ten.
>     By the roller being in a different place. And of course anywhere
>     in-between.
>
>     I am learning this combo of different values of plate cap and the
>     inductor, is what determines the level of that mysterious "Q" but
>     then
>     again I may be wrong here.
>
>     The AMP is like 99% ready to be put into service,. Just need the help
>     with this "Q" Stuff, and to discover what to do with the plate cap
>     and
>     "L" values for optimal performance.
>
>     Joe WB9SBD
>
>     On 10/11/2021 4:49 AM, Rob Atkinson wrote:
>     > Why do some of you guys want to jack up the plate v. on your 3-500s?
>     > The power difference won't be noticed and you'll create a cascade of
>     > problems.  You still have the same plate dissipation and plate
>     current
>     > limits.  The pi network won't work, the DC blocking caps may become
>     > marginal, the power supply filter cap bank may get stressed and the
>     > IMD spec. gets worse.  If you want to jack up the B+ get a 3-1000Z.
>     >
>     > 73
>     >
>     > Rob
>     > K5UJ
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